Transcription

• Primary structure of an RNA molecule: sequence of nucleotides; secondary structure: the way in which the RNA molecule folds up into a three-dimensional shape, determined by hydrogen bonding between complementary bases on the same strand

  
• Transcription process in a gene:

  • Promoter region: where RNA polymerase binds to the DNA and starts transcription
  • RNA-coding region: where the RNA polymerase transcribes the DNA into RNA
  • Terminator region: where the RNA polymerase terminates transcription and releases the RNA transcript

  
• Types of RNA polymerases in eukaryotes:

  • Eukaryotic RNA polymerases transcribe different types of RNA molecules:

  1. RNA polymerase I: found in the nucleolus, transcribes rRNA

  2. RNA polymerase II: found in the nucleoplasm, transcribes mRNA

  3. RNA polymerase III: found in the nucleoplasm, transcribes tRNA and other small RNAs

  4. RNA polymerase IV: found in plants, transcribes some siRNAs

  5. RNA polymerase V: found in plants, transcribes RNAs for heterochromatin formation

  
• RNA, Consisting of a Single Strand of Ribonucleotides, Participates in a Variety of Cellular Functions

  • RNA: evidence suggests RNA was original genetic material
  • Ribozymes: catalytic RNA
  • The structure of RNA
  • Primary structure
  • Secondary structure
• RNA

  A) thymine

  B) hydroxyl

  
• DNA vs RNA compared

  A) ribose

  B) no

  C) many types

  D) degraded

  
• Classes of RNA:

  • Ribosomal RNA: rRNA
  • Messenger RNA: mRNA
  • Transfer RNA: tRNA •
  • Small nuclear RNAs: snRNAs •
  • Small nuclear ribonucleoproteins: snRNPs •
  • Small nuclear RNAs: snoRNAs •
  • Small cytoplasmic RNAs: scRNAs •
  • MicroRNAs: miRNAs •
  • Small interfering RNAs: siRNAs •
  • Piwi-interacting RNAs
• Classes of RNA:

  A) rRNA

  B) mRNA

  C) tRNA

  D) snRNA

  E) snoRNA

  F) miRNA

  G) siRNA

  H) piRNA

  I) crRNA

  
• Is the Synthesis of an RNA Molecule from a DNA Template?

  • The template: •
  • The transcribed strand: template strand •
  • The transcription unit •
  • A promoter •
  • RNA-coding sequence •
  • Terminator
• Both / Proka / Euka /

  A) mRNA

  B) rRNA

  C) tRNA

  D) pre-mRNA

  E) snRNA

  F) snoRNA

  G) miRNA

  H) siRNA

  I) piRNA

  J) crRNA

  
• RNA Synthesis

  A) complementary

  B) antiparallel

  C) 5

  D) 3

  E) nontemplate

  
• Gene transcription to RNA

  A) 5

  B) 3

  C) 3

  D) 5

  
• Transcription

  A) promoter

  B) rna

  C) terminator

  D) start

  E) termination

  F) nontemplate

  G) template

  
• Function of the promoter

  1. Serves as sequences to which the transcription apparatus binds
  2. Determines the first nucleotide that is transcribed into RNA
  3. Determines which DNA strand is template
• Transcription Is the Synthesis of an RNA Molecule from a DNA Template

  • Initiation - The substrate for transcription:
  • Ribonucleoside triphosphates—rNTPs added to the 3¢ end of the RNA molecule.
• The transcription apparatus:

  Bacterial RNA polymerase: five subunits made up of the core enzyme:

  1. Two copies of α
  2. Single copy of β
  3. Single copy of β'
  4. A stabilize enzyme: ω
  5. The sigma s factor: binding to the promoter when transcription starts
• RNA Synthesis: initiation

  A) primer

  B) 3

  C) transcription bubble

  D) rewinds

  
• RNA Synthesis: Initiation

  A) Sigma

  B) Core

  C) holoenzyme

  
• Transcription Is the Synthesis of an RNA Molecule from a DNA Template

  • Initiation
  • The substrate for transcription: Ribonucleoside triphosphates—rNTPs added to the 3' end of the RNA molecule (ATP, GTP, UTP, CTP)
  • The transcription apparatus: Eukaryotic RNA polymerases